1. Field of the Invention
The present invention relates to a polarizing plate that can form a liquid crystal display (hereinafter described as LCD) in which brightness irregularity is difficult to occur, and the liquid crystal display has a screen with optimized color tones.
2. Description of the Related Art
Polarizing plates have been used widely for liquid crystal displays, and the demand for the polarizing plates has been increased remarkably. Furthermore, high-value-added polarizing plates, e.g., a polarizing plate having an optical compensation function, have been used, and demand for display quality has further increased when considering some aspects such as a wide visual angle.
A polarizing plate for the above-described use can be prepared typically by laminating a protective film of triacetylcellulose or the like on both surfaces of a polarizing film made of a polyvinyl alcohol-based film (hereinafter described as a PVA-based film) in which iodine or a dichroic dyestuff is adsorbed and oriented (see JP 14(2002)-028939A and JP 13(2001)-343529A). A known optically compensating retardation plate has a triacetylcellulose film supporting an optically anisotropic layer formed by incline-orientating a discotic liquid crystal polymer. This optically compensating retardation plate will be adhered to a polarizing plate so as to provide a wide-visual-angle polarizing plate. Alternatively, the optically compensating retardation plate will be adhered directly to a polarizing film by using an adhesive (see JP 06(1994)-214116A and JP 07(1995)-98411 A).
However, a liquid crystal display having a panel equipped with a polarizing plate (especially the above-described wide-visual-angle polarizing plate) in crossed Nicols has a problem of brightness irregularity. The brightness irregularity means a lowering contrast, and it is caused by leakage of light beams from the backlight in the vicinity of the periphery of the display screen.